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Commit 25496cae authored by Thomas Renninger's avatar Thomas Renninger Committed by Len Brown
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ACPI: Only use IPI on known broken machines (AMD, Dothan/BaniasPentium M) 



Use IPI for blacklisted CPUs, add parameter IPI vs LAPIC

Currently, Linux disables lapic timer for all machines with C2 and higher
C-state support.

According to Intel only specific Intel models (Banias/Dothan) are broken
in respect of not waking up from C2 with lapic.

However, I am not sure about the naming of the parameter and how it
could/should get integrated into the dyntick part
(CONFIG_GENERIC_CLOCKEVENTS). There, a more fine grained check (TSC
still running?, ..) is needed? Does this make sense (always use
CLOCK_EVT_NOTIFY_BROADCAST_ON, but use OFF if forced by use_ipi=0:
clockevents_notify(use_ipi ? CLOCK_EVT_NOTIFY_BROADCAST_ON :
CLOCK_EVT_NOTIFY_BROADCAST_OFF, &pr->id);

Signed-off-by: default avatarThomas Renninger <trenn@suse.de>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent db98e0b4

drivers/acpi/processor_idle.c

+29 −9
Original line number Diff line number Diff line
@@ -89,6 +89,12 @@ module_param(nocst, uint, 0000); 
static unsigned int bm_history __read_mostly =

    (HZ >= 800 ? 0xFFFFFFFF : ((1U << (HZ / 25)) - 1));

module_param(bm_history, uint, 0644);



static unsigned use_ipi = 2;

module_param(use_ipi, uint, 0644);

MODULE_PARM_DESC(use_ipi, "IPI (vs. LAPIC) irqs for not waking up from C2/C3"

		 " machines. 0=apic, 1=ipi, 2=auto\n");



/* --------------------------------------------------------------------------

                                Power Management

   -------------------------------------------------------------------------- */
@@ -260,9 +266,8 @@ static void acpi_cstate_enter(struct acpi_processor_cx *cstate) 


/*

 * Some BIOS implementations switch to C3 in the published C2 state.

 * This seems to be a common problem on AMD boxen, but other vendors

 * are affected too. We pick the most conservative approach: we assume

 * that the local APIC stops in both C2 and C3.

 * This seems to be a common problem on AMD boxen and Intel Dothan/Banias

 * Pentium M machines.

 */

static void acpi_timer_check_state(int state, struct acpi_processor *pr,

				   struct acpi_processor_cx *cx)
@@ -276,8 +281,17 @@ static void acpi_timer_check_state(int state, struct acpi_processor *pr, 
	if (pwr->timer_broadcast_on_state < state)

		return;



	if (cx->type >= ACPI_STATE_C2)

	if (cx->type >= ACPI_STATE_C2) {

		if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)

			pr->power.timer_broadcast_on_state = state;

		else if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&

			  boot_cpu_data.x86 == 6) &&

			 (boot_cpu_data.x86_model == 13 ||

			  boot_cpu_data.x86_model == 9))

		{

			pr->power.timer_broadcast_on_state = state;

		}

	}

}



static void acpi_propagate_timer_broadcast(struct acpi_processor *pr)
@@ -292,10 +306,16 @@ static void acpi_propagate_timer_broadcast(struct acpi_processor *pr) 
#else

	cpumask_t mask = cpumask_of_cpu(pr->id);



	if (use_ipi == 0)

		on_each_cpu(switch_APIC_timer_to_ipi, &mask, 1, 1);

	else if (use_ipi == 1)

		on_each_cpu(switch_ipi_to_APIC_timer, &mask, 1, 1);

	else {

		if (pr->power.timer_broadcast_on_state < INT_MAX)

			on_each_cpu(switch_APIC_timer_to_ipi, &mask, 1, 1);

		else

			on_each_cpu(switch_ipi_to_APIC_timer, &mask, 1, 1);

	}

#endif

}
@@ -1013,13 +1033,13 @@ static int acpi_processor_power_verify(struct acpi_processor *pr) 


		case ACPI_STATE_C2:

			acpi_processor_power_verify_c2(cx);

			if (cx->valid)

			if (cx->valid && use_ipi != 0 && use_ipi != 1)

				acpi_timer_check_state(i, pr, cx);

			break;



		case ACPI_STATE_C3:

			acpi_processor_power_verify_c3(pr, cx);

			if (cx->valid)

			if (cx->valid && use_ipi != 0 && use_ipi != 1)

				acpi_timer_check_state(i, pr, cx);

			break;

		}